JPH0958902A - Sheet feeding device utilizing air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more positively detect a thickness of sheets even when sheets such as a manuscript paper are fed by utilizing air. SOLUTION: A sheet P on a paper placing tray 151 is raised through a lowering and elevating mechanism, and stopped when a reference position for the most suitable paper feeding is detected by a detecting sensor. Then, the sheet is lowered a fixed distance from the position to stop the paper placing tray 151. In this state, an attraction means 159 of a paper feeding belt 152 is operated, and the suction state of the uppermost sheet P is detected by the suction detecting sensor 50. When the suction state of the sheet is not detected, the paper placing tray 151 is slowly elevated. In response to the position of the paper placing tray 151, namely the uppermost sheet P at the time when the section of the sheet is detected by the suction detecting means 50 in answer to the state where the tray is raised, a thickness of the sheet is discriminated. In response to thickness detected, the air quantity or conveyance of the paper feeding belt is controlled, and thus stable paper feeding can be performed without being affected by the thickness of the sheets.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for feeding a stack of sheets cut to a predetermined size to a predetermined position, and in particular, a sheet fed by using air. Regarding a paper feeding device.

[0002]

2. Description of the Related Art Conventionally, according to an image recording apparatus, a sheet-shaped recording sheet is conveyed to a recording position, a recording image is formed on the sheet, and then the sheet is ejected to the outside of the apparatus. For example, a copying apparatus in which an image of an original is directly formed on a recording medium, the image on the recording medium is transferred to a sheet-shaped conveyed sheet, and the sheet after the transfer is discharged to the outside of the apparatus through a fixing step. Etc.

In the above copying apparatus, a document is placed at a predetermined position, that is, an exposure position, and the document image at the exposure position is projected on a photoconductor which is a recording medium. In this case, in order to save the trouble of manually placing the sheet original at the exposure position,
There is a copying apparatus including an automatic document feeder for stacking sheet originals on an original tray and automatically conveying the sheet originals on the original tray to the exposure position.

Among the automatic document feeders described above, when the image exposure of the sheet document at the exposure position is completed, the document is fed from the exposure position and re-transported to the exposure position again to form an image. Some are returned to the loading tray. There is also a recirculating document transport device (Recirculating Document Handler; hereinafter referred to as RDH) that returns the sheet document from the document mounting tray to the exposure position and from the exposure position to the document mounting tray.

There is also a recording (or copying) device for performing not only sheet originals but also double-sided recording (copying) for forming images on both sides of a cut sheet or composite recording for forming images on the same side of a sheet by superimposing. . In the copying machine having the double-sided and synthesizing function, before discharging the paper on which the original image is formed on one surface to the outside of the apparatus, the paper is temporarily discharged and stored in the intermediate tray, and the paper in the intermediate tray is re-described above. The image is conveyed to the image forming position of the copying machine and an image is formed on the opposite surface or the same surface.

As described above, in order to feed the sheets to the target position, a sheet feeding device is provided for feeding the sheets stacked on various trays from the position. That is, in the RDH, the stacked sheet originals are fed in, and in the sheet paper, not only the intermediate tray, but also the sheet feeding device for feeding the sheet paper stacked for recording an image is fed to the tray to be stacked. Correspondingly, each is provided independently.

As an example of this paper feeding device, a device that more reliably feeds one sheet by using air has been proposed and put into practice. In this case, it is important to adjust the flow rate of the air according to the thickness of the sheet. In other words, if the thickness of the sheet is large, one sheet can be fed more reliably by increasing the air amount, and if the sheet is thin, if the air amount is large, a plurality of sheets are adsorbed at the same time instead of one sheet. , Sometimes double-fed.

In view of the above, Japanese Patent Laid-Open No. 6-40604 discloses a method of sucking a sheet by using air and feeding the sucked sheet. It is specified that the actual sheet thickness is calculated from the reduction amount of the position, and when the sheet thickness exceeds a certain amount, it is detected as a double feed. Further, in this publication, the sheet thickness is detected according to the time when the sheet is adsorbed, and when the thickness exceeds a certain amount, it is detected that the sheet is double fed.

As described above, conventionally, the means for detecting the sheet thickness is provided, and accordingly, the double feeding of the sheets is detected to ensure the single sheet feeding.

[0010]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the sheet feeding device described in Japanese Patent No. 604, air is used to feed a sheet, the sheet thickness is detected in the sheet feeding at this time, and double feeding can be detected based on this thickness. . However, there is no disclosure about performing control according to the sheet thickness in order to more reliably perform single-sheet feeding with air.

In particular, even if the thickness of the sheet is detected,
It is determined whether or not the fed sheets are in the double feed state. If the sheets are in the double feed state, the sheet feed is stopped, and at the same time, the operation of the image forming apparatus is stopped. Therefore, there is no idea to perform control to reliably feed one sheet.

Further, in the conventional sheet thickness detection,
Since the thickness is detected based on the number of sheets after being fed, it is impossible to detect the thickness until a certain number of sheets are fed. Therefore, it is not possible to detect the sheet thickness before being fed, and there is no idea to control the sheet feeding according to the detected thickness.

Therefore, in the above publication, air is sucked, the suction time of the uppermost sheet is measured, and the thickness of the suction sheet is determined. However, depending on the amount of sucked air and the position of the sheet. And the adsorption time will be different. Therefore, the sheet thickness detection becomes inaccurate. In particular, although the sheet to be fed is maintained at a constant height, it is generally not raised to that position each time one sheet is fed, but is generally controlled to be raised after a certain amount of reduction. . Therefore, the height of the sheet is not constant, and the suction time of the sheet changes each time. Moreover, in order to detect the thickness of the sheet, it is necessary to separately provide a means for measuring the time.

In view of the above points, the present invention provides a sheet feeding device capable of more reliably detecting the thickness of a sheet. Further, the present invention provides an apparatus for feeding a sheet using air and an apparatus capable of detecting the sheet thickness by directly using the parts and the like conventionally provided.

Another object of the present invention is to control the flow rate of air or paper feed in accordance with the detected sheet thickness.
The purpose is to perform sheet feeding more reliably.

[0016]

A sheet feeding device of the present invention is a sheet feeding device for feeding the uppermost sheet on a loading tray, and the uppermost sheet is attracted to the sheet feeding device by air suction. Suction means for causing, air ejection means for blowing air to the leading edge of the sheet to be fed and separating and separating, and driving means for driving the sheet feeding means to feed the sheet adsorbed to the sheet feeding means, In the sheet feeding apparatus having the above-mentioned, in order to detect the thickness of the sheet, the above-mentioned placing tray is provided so as to be movable up and down, and the raising and lowering control means for raising and lowering the placing tray and the above-mentioned placing tray are raised. At the time, a position detection sensor that detects a state in which the uppermost sheet on the loading tray reaches the paper feed reference position, and the loading tray is lowered by a certain distance in response to the reference position detection by the position detection sensor, In the lowered position The control means for operating the suction means to perform the suction of the uppermost portion, the suction detection sensor for detecting the state in which the sheet is sucked by the sheet feeding belt, and the above-mentioned in response to the suction detection of the suction detection sensor. A sheet thickness discriminating means for discriminating the sheet thickness according to the position of the uppermost sheet on the placing tray.

In the above structure, since the sheet thickness is detected according to the position of the uppermost sheet at the time when the uppermost sheet is adsorbed, the sheet feeding is performed without adding any special means. This can be easily detected by controlling the raising and lowering of the loading tray in advance before the paper is printed.

Further, another sheet feeding device of the present invention is a sheet feeding means for feeding the uppermost sheet on the loading tray, and a suction means for sucking the uppermost sheet to the sheet feeding means by air suction. And air driving means for blowing air to the leading edge of the fed sheet to float and separate, and driving means for driving the sheet feeding means and feeding the sheet adsorbed to the sheet feeding means. In the sheet feeding device, in order to detect the thickness of the sheet, a mounting tray is provided so as to be movable up and down, and elevating control means for raising and lowering the mounting tray, and a mounting tray when the mounting tray is raised. A position detection sensor for detecting a state where the uppermost sheet reaches the paper feed reference position; a control means for operating the air ejecting means for floating in response to the reference position detection by the position detection sensor; Of sheet A buoyant position detection sensor for detecting the lift position, characterized by comprising a sheet thickness determination means for determining the thickness of the sheet, the in response to an output from the flotation position detection sensor.

Also in this sheet feeding device, the thickness of the sheet can be detected before the feeding, in the state that the uppermost sheet position is the reference position. In this case, in particular, a sensor for detecting the floating position of the uppermost sheet is provided, and the seat pressure can be detected according to the output from the sensor.

Therefore, in the above-described sheet feeding device, the amount of air suction or the amount of air ejection is controlled according to the detection of the thickness, so that the sheet can be floated at a fixed position regardless of the sheet thickness. Also, since the suction can be performed reliably, one sheet feeding or reliable sheet feeding can be performed, and stable sheet feeding can be performed.

Further, if the acceleration of the sheet feeding means is controlled while the sheet is sucked, the sheet can be fed without being slipped by the sheet regardless of the thickness of the sheet, so that the sheet can be fed stably. become.

Further, if an optical sensor is used as a sensor for detecting the floating position of the sheet in order to detect the thickness of the sheet, its output changes depending on the position where the sheet is present. Instead, it can also be used as a sensor for detecting the reference position for optimum paper feeding of the uppermost sheet.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a sheet feeding device according to the present invention will be described below with reference to the drawings. Further, in the following embodiments, a copying apparatus will be described as an example of the recording apparatus, but the present invention is not limited to such an apparatus.
In other words, the present invention can be applied to all apparatuses that stack cut sheets of paper or originals on a tray or a paper feed cassette, and feed the stacked uppermost sheet.

FIG. 1 is a schematic sectional view showing an example of a copying apparatus to which the sheet feeding apparatus of the present invention is applied, FIG. 2 is a sectional view showing an example of the sheet feeding apparatus of the present invention, and FIG. 3 is a top view thereof. Is.

In FIG. 1, the copying apparatus is a copying apparatus main body 1
And a document processing unit, that is, an RDH 30 which is a document feeding device for sequentially transporting the document to the document exposure position and returning it to the original position after processing.

An optical system 2 for exposing a document image for image formation is arranged on the upper portion of the copying apparatus main body 1. The optical system 2 includes a copy lamp 3 including a halogen lamp, a plurality of mirrors 4 to 7, a zoom lens 8 and the like.
And

A photoconductor 9 having a photoconductive layer on the surface of a drum-shaped recording medium is rotatably arranged below the optical system 2. Various devices for forming an image are arranged around the photoconductor 9.
For example, a charger 10, a developing unit 11, a transfer unit 12, a cleaning unit 13, a static eliminator 14 and the like are arranged.

When forming an image, first, the surface of the photoreceptor 9 is uniformly charged to a predetermined potential by the charger 10, and then the original is irradiated by the optical system 2 to reflect the reflected light to the mirror and the lens. The image is projected on the surface of the photoconductor 9 via. As a result, an electrostatic latent image corresponding to the image of the original is formed on the photoconductor 9, and toner is attached to the developing unit 11 in order to visualize the latent image to form a toner image. The toner image is transferred onto a sheet fed by one sheet feeding device selected from a plurality of roller type sheet feeding devices 15a or an air type sheet feeding device 15. Therefore, the operation of the transfer device 12 is appropriately performed on the surface of the sheet that is appropriately sent to the transfer position where the transfer device 12 is disposed via the registration roller 16 that starts feeding in synchronization with the rotation of the photoconductor 9. Thus, the toner image formed on the photoconductor 9 is electrostatically transferred.

After that, the sheet of paper is peeled off from the photoconductor 9 and sent to the fixing section 18 through the suction / conveyance means 17. The fixing section 18 is composed of, for example, a heat roller whose upper side in contact with the toner image is heated to a constant temperature by at least a heat source, and a pressure roller which presses the heat roller with an appropriate pressure. , The toner image on the sheet of paper is heated and fixed. The fixed sheet of paper on which an image has been formed is discharged onto a sorter 20 for aligning the sheets of paper connected to the discharge port 19 of the copying apparatus main body 1 in page order, and also forms a sheet of image. It is sent to a transport means 22 for transporting to an intermediate tray 21 provided at the lower part of the copying apparatus main body 1 for forming an image again on the opposite surface or the same surface. The sheet paper carried by the carrying means 22 is carried out to the intermediate tray 21 via the switchback carrying section 23, or as it is via the carrying section 24. That is, by passing through the switchback transport unit 23, the feeding direction of the leading edge and the trailing edge of the sheet of paper is reversed and the front and back sides are reversed, and the intermediate tray 21 is transported through the transport unit 24.
It is carried out to, but if it goes through the transport unit 24 as it is,
The sheet is conveyed to the intermediate tray 21 without being turned upside down.

The intermediate tray 21 is provided with a placing table 25 for placing sheets and a sheet feeding means 27 for sucking and feeding the sheet sheets on the placing table 25 by using air.
The sheet of paper fed is the registration roller 16 described above.
A transport roller 27 that feeds the sheet is disposed on the downstream side of the sheet transport path.

The sheet paper accommodated in the intermediate tray 21 is sequentially fed, for example, one by one from the lowermost one by the action of the paper feed means (paper feed belt) 27, and the above-mentioned paper is fed through the transport rollers 27 and various transport means. The image is sent to the registration roller 16 in the image forming unit.

On the other hand, the optical system 2 transfers the image of the original to the photosensitive member 9
In addition to the RDH 30, the original placed on the original table 29 made of a transparent glass plate is optically scanned in order to project the image onto the original. Therefore, a first mirror base (not shown) composed of the lamp 3 and the mirror 4 and a second mirror base (not shown) composed of the mirrors 4 and 5 are moved in the arrow A direction,
The document on the document table 29 is optically scanned and sequentially projected onto the rotating photoconductor 9.

In addition to the image exposure on the original table 29, the optical system 2 also positions the first exposure section 31 and the second exposure section 32 for image exposure in accordance with the document conveyance by the RDH 30. Can be moved to. That is, RDH3
The first exposure unit 31 and the second exposure unit 32, which are made of transparent plates, are arranged side by side in sequence while the sheet document is being conveyed at 0. The optical system 2 is selectively fixed at positions corresponding to the first exposure section 31 and the second exposure section 32. Therefore, by fixing the first mirror base and the second mirror base at the positions shown in the figure, the image of the document conveyed on the first exposure unit 31 is projected onto the surface of the photoconductor 9. Further, by moving the first mirror base and the second mirror base of the optical system 2 to the second exposure unit 32 and fixing them in that position, the image on the opposite surface of the sheet original conveyed to the second exposure unit 37 is displayed. It can be projected on the photoconductor 9.

The sheet feeding apparatus according to the present invention is a sheet feeding apparatus 15 for feeding the sheet sheet to the position of the registration roller 16, a sheet feeding apparatus for feeding the copied sheet sheet accommodated in the intermediate tray 21, 2 and 3 show the details of the sheet feeding device that feeds the sheet originals in the RDH from the position where the sheet originals are stacked to the conveying path, and that feeds the sheet using air. The structure of the sheet feeding device 15 that feeds the image to the image forming position in order to form an image on the sheet in the copying machine will be described below.

The sheet feeding device 15 is placed on a placing tray 151 located in a sheet storage section 150 provided so as to be drawn out from the copying apparatus (it can be drawn out in a direction opposite to the sheet feeding direction). A sheet feeding belt 1 which is a sheet feeding unit provided with a suction unit corresponding to the stacked sheets P.
52 are arranged. The paper feeding belt 152 is stretched between the driving roller and the driven rollers 152a and 152b, and is directly connected to the shaft of the driving roller 152a in FIG.
It is possible to feed the adsorbed sheet to a target position by being driven via the drive motor or the clutch 153 that transmits the rotational force from the drive motor shown in FIG.

The paper feed belt 152 is divided into a plurality of parts as shown in FIG. 3, and a large number of openings 152c are formed for adsorbing a sheet by sucking air.
A suction unit 155 that constitutes suction means 154 that sucks air is provided in the paper feed belt 152.

As shown in FIG. 4, the suction means 154 is provided with an opening / closing valve 158 for adjusting the suction force in a suction duct 157 which constitutes a flow path for suction by a suction fan 156, and the suction duct 157 is provided with the above-mentioned valve. The suction unit 155 is connected. The suction portion 155 is formed with suction openings 155a formed corresponding to the above-described respective sheet feeding belts 152, and a sheet is sucked by performing air suction through the openings 152c of the sheet feeding belts 152. Paper feeding belt 152
Air ejecting means 160 for blowing air onto the stacked sheets to levitate the sheets is provided with respect to the air sucking means 154 which is adapted to adsorb the sheets. The discharge means 160 is arranged such that the discharge section 161 faces the front surface in the sheet feeding direction of the stacked sheets, and the discharge section 161 is provided with two types of nozzles for discharging air. One nozzle 162 is formed in a shape that blows out in the direction of the stacked sheets in order to separate and float the stacked sheets, particularly the uppermost sheet and the lower sheet, and the other nozzle 163 is sucked. In order to separate the plurality of sheets, air is blown in the direction of the leading edge of the sheet on the side of the sheet feeding belt 152.

The discharge part 161 is a discharge fan 16
Discharge duct 16 forming a flow path of air blown out by 4
The discharge duct 165 is provided with an opening / closing valve 166 for adjusting the discharge amount of air. Further, on the nozzle 163 side, an opening / closing valve 167 for controlling the ejection of air is provided in order to separate the sheet after being sucked.

According to the sheet feeding device 15 having the above-described structure, in response to the sheet feeding command, the discharging means 160 first operates to levitate the uppermost stacked sheet. Therefore, the discharge fan 164 is driven and at the same time the on-off valve 1
66 is opened, air is blown from the nozzle 162, and the uppermost sheet is levitated. Then, the suction means 154 on the side of the sheet feeding belt 152 is operated at the same time as the discharging operation or after the uppermost sheet is floated. The air is sucked through the suction opening 155a of the suction unit 155 by driving the suction fan 156, and the floated uppermost sheet is sucked onto the sheet feeding belt 152.

At the same time as this suction operation or at the same time as the above-mentioned floating operation, in order to prevent the feeding of a plurality of sheets to be sucked, the on-off valve 167 is opened to blow air to the sucked sheet leading end portion. Air is ejected from the nozzle 163. As a result, the sheets other than the uppermost one of the plurality of sucked sheets are separated, and only the uppermost sheet is sucked by the sheet feeding belt 152. After that, the paper feed belt 15
The sheet is fed by rotating the driving roller 152b to drive the sheet 2.

Here, in the sheet feeding apparatus of the present invention, the point is to detect the thickness of the sheet to be fed. The structure for detecting the thickness of the sheet will be described below. As shown in FIG. 6, a mounting tray 151 is provided so as to be movable up and down, and a wire 40 that constitutes an elevating mechanism is vertically stretched on both sides of the mounting tray 151 in order to perform the vertical movement. . Wire 40 is drive pulley 41 and 4
It is bridged over two driven pulleys 41a to 41d, and is fixed to the above-mentioned mounting tray 151 by two fixing portions indicated by reference numeral 42. Therefore, the drive pulley 41 is
When it is rotationally driven clockwise, the loading tray 151 is lowered, and when it is rotationally driven counterclockwise, it is raised.

A position detecting sensor 43 for detecting the lower limit position of the loading tray 151 is provided in the lower part of the sheet storage portion in which the loading tray 151 moves up and down. That is,
The position detection sensor 43 is composed of a micro switch, and its actuator is in contact with the uppermost sheet P stacked on the mounting tray 151 to move, thereby detecting its position and optimally feeding the uppermost sheet P. It is provided to hold the value at the reference position.

Further, similarly to the position detection sensor 43, the upper limit detection sensor 44 for detecting the upper limit of the tray 151 described above.
Is disposed on the upper portion of the sheet storage portion 150. The upper limit detection sensor 44 is provided to prevent the uppermost sheet P from moving beyond the reference position and further rising, and outputs a detection signal forcibly stopping the rising operation in the detection.

Then, a lower limit detection sensor 45 for detecting the position of the uppermost sheet P stacked on the loading tray 151 is arranged at an appropriate position at the bottom of the accommodating portion 150.
The lower limit detection sensor 43 is used when moving the loading tray 151 to the lower limit position when stacking the sheets on the loading tray 151, and when the loading tray 151 is detected (ON), the loading tray 151 is detected. Stop the descent of.

In order to move the loading tray 151 up and down via the wire 40, the drive pulley 41 is connected to the rotary shaft of a lifting motor 46 directly or via a speed reducing mechanism or the like. A slit disk 47 is fixed to the rotation shaft of the lifting motor 43, and an optical sensor 48 for slit detection is used to grasp the rotation speed (rotation position) of the motor by counting the number of slits. Is provided. Therefore, the mounting tray 151 that is moved up and down can confirm the rotational position of the motor 46 by counting the number of slits.

As the control of the lifting mechanism, if the loading tray 151 is pulled out in order to replenish the sheets, and the pulling out is detected (not shown), the lifting motor 46, which is the lifting mechanism, In FIG. 6, it is driven to rotate clockwise. As a result, the loading tray 151 is lowered, and the lower limit detection sensor 43 detects (ON) the lower limit position, whereby the rotation of the motor is stopped, and the loading tray 15 is stopped at that position.
1 stops. In this state, sheets can be replenished or replaced.

When the above replenishment is completed, the loading tray 1
When the insertion state of 51 is detected, the raising / lowering motor 46 is rotationally driven counterclockwise in order to raise the loading tray 151 in response to the detection signal. As a result, the loading tray 151 rises, and when the placed uppermost sheet is detected (ON) by the position detection sensor 43, the operation of the motor 46 is stopped to stop the lifting operation. As a result, the placed uppermost sheet is held at the reference position where paper can be fed. When this operation is completed, the preparation for the paper feeding operation is completed. When the position detection sensor 43 detects the above position and a further upward drive command is given,
The upper limit detection sensor 44 detects it and operates to prevent further increase, stopping the rotation of the motor 46.

Further, in the present invention, in order to detect the thickness, the suction detection sensor 50 for detecting the sheet P sucked on the sheet feeding belt 152 is arranged at the position shown in FIGS. 4 and 5. That is, it is arranged near the leading edge of the sheet to be fed and between the divided sheet feeding belts 152. The adsorption detection sensor 50 is an optical sensor and has a configuration in which the sheet P is irradiated with light from a light emitting element and the light receiving element receives the reflected light.
The output increases as the value approaches. The suction detection sensor 50 has been conventionally provided, and when the suction state of the sheet is detected, the traveling drive of the sheet feeding belt 152 is started.

(First Embodiment) Next, the control operation for detecting the sheet thickness according to the present invention will be described with reference to the flowchart of FIG.

First, in order to detect the thickness of the stacked sheets P, the above-described operation for replenishing the loading tray 151 with sheets is executed. As a result, the operation of detecting the thickness of the sheet P is executed in advance before the start of sheet feeding.

Therefore, whether or not the loading tray 151 can be raised is checked in step S1. This is to replenish the sheets after pulling out the loading tray 151,
By receiving a signal from a detection unit (not shown) that detects the operation of inserting the loading tray 151, the process proceeds to step S2 to start the operation of raising the loading tray 151. This is the lifting motor 4 as described above.
This is executed by rotating 6 in the counterclockwise direction.

Here, when the mounting tray 151 is present at the reference position when the power of the copying apparatus 1 is turned on,
When the position detection sensor 43 detects it, the lowering operation is once executed without performing the ascending operation. As a result, a signal capable of rising is output when the position detection sensor 43 is turned off. By checking this, the process moves to the next step.

As the loading tray 151 is lifted as described above, the position of the uppermost sheet P is raised, and when it reaches the reference position, the position detection sensor 43 detects it. Whether or not the position detection sensor 43 is turned on is checked in step S3, and when the uppermost sheet P is detected by the position detection sensor 43, the motor 46 is stopped to stop the raising of the loading tray 151. Is stopped, and subsequently, the elevating motor 46 is rotationally driven in the clockwise direction (S4) in order to execute the descending control of the mounting tray 151 to a predetermined position.

In the lowering operation described above, the uppermost sheet P is lowered by a predetermined distance (L) from the reference position at which it can be fed. For example, the uppermost sheet P is lowered beyond at least the position where the position detection sensor 45 is turned off. The distance (L) is lowered by, for example, about 6 mm. Since the slit of the slit disk 47 provided on the lifting motor 46 is detected by the optical sensor 48 as described above, the confirmation of this lowered position counts the detected slit signal. Therefore, when the loading tray 151 is moved up and down, if the slit signal changes by 1 mm by counting 10 for example, when the slit signal is counted 60, it can be confirmed that the fixed distance L is lowered.
In this way, by lowering the loading tray 151 by a certain distance L, the position of the uppermost sheet P is also held at a position lowered by a certain distance L from the reference position.

Upon completion of the above-mentioned confirmation, in order to stop the lowering operation of the loading tray 151, the lifting motor 4 is moved.
The operation of 6 is stopped (S6). Then, in order to suck the uppermost sheet P, the suction fan 156 is driven to open the open / close valve and start the suction operation. In this case, the operation of the ejection means 160 is stopped. After starting the suction operation, the sheet is sucked (adsorbed) on the sheet feeding belt 152.
Whether or not it is detected is detected by the suction detection sensor 50.

The confirmation of the suction state is continued until the suction operation time T reaches the preset suction reference time t. The suction reference time t is the same as that of the uppermost sheet P for the sheet feeding belt 152.
It is set to the time of adsorption to the side, for example 100m
It is set to about sec. If the suction operation is not confirmed within the time t (S9), in order to stop the suction operation, the driving of the suction fan 156 described above is stopped, and the opening / closing valve 158 is also closed (S1).
0). Then, under the predetermined conditions, the above-mentioned storage tray 15
1 is increased (S11). The confirmation of this rise is also performed by counting the slit signal of the slit disk 47 for confirming the rotation speed of the lifting motor 46 as described above. For example, to raise about 2 mm,
The ascending operation is stopped under the condition that the slit signal is counted 20 (S6). As a result, the uppermost sheet P is held at a position elevated by 2 mm.

When it is confirmed that the ascending operation is completed (S12), the process returns to step S6 and the above operation is repeated.
In this operation, in step S8, it is confirmed whether or not the sheet P is attracted to the sheet feeding belt 152. Here, the reference time t for the sheet P to continue the suction operation described above.
If detected inside, the operating state of the position detection sensor 43 is confirmed in step S13. At this time, the position detection sensor 4
3 is turned on, that is, turned on when the uppermost sheet P is lifted to a predetermined position (for example, a reference position). If it is in the ON state in this detection state, it is difficult to adsorb the uppermost sheet, so that the mounting tray 151 moves from step S6 to step S6.
S12 is sequentially repeated and gradually raised, and the uppermost sheet P
The position of is also gradually raised, and it can be determined that the sheet P is in a thick state (S14).

On the other hand, if the suction state is detected by the suction detection sensor 50 before the position sensor 43 is turned on, it means that the sheet P is easily sucked and the loading tray 151 is Since the position where the sheet is not raised so much, that is, the position of the uppermost sheet P is low, it can be determined that the sheet is a thin sheet (S15). This is step S
In 3, the state was raised to the reference position, then lowered,
To confirm the suction state of the uppermost sheet P, and to detect the thickness of the sheet P at the position where the sheet is sucked. In this case, if the sheet is thin,
It will be adsorbed at a position lower than the reference position,
When the sheet is thick, the suction operation becomes difficult, and the sheet can be sucked by raising the sheet at the reference position or further, which is an effective means for detecting the thickness.

As described above, according to the present invention, the mechanism for raising and lowering the sheet P and the sensor for detecting the sheet position as described above are conventionally provided, and are specially provided separately. is not. Then, the stacking tray 151 on which the sheets are stacked is lowered from the reference position, and the position of the uppermost sheet P at the stage of gradually rising from this position is grasped, and the sheet is detected in accordance with the suction detection of the uppermost sheet P. The point of detecting the thickness of is very new.

Here, in the process of gradually rising from the suction start position lowered from the reference position without judging the thickness of the sheet from the operating state of the position detection sensor 43, the sheet is sucked at the raised position. Can determine the thickness of.
For example, when the loading tray 151 is moved up by 2 mm, the suction operation is performed every time when the loading tray is moved up by 2 mm. Therefore, the thickness can be determined at the time of suctioning. That is, if the suction of the sheet is detected in a state where the sheet P is lowered by 6 mm from the reference position, the sheet P is an ultra-thin sheet (for example, a sheet thinner than 60 g / m ² ), and the suction of the sheet is confirmed in a state of being further raised by 2 mm. And a thin sheet (for example, a sheet having a weight of about 60 g / m ² ), and a sheet having a normal thickness (for example, 7
(Sheet of 0 to 80 g / m ² ), and a thick sheet when adsorbed at the reference position (sheet having a thickness exceeding 90 g / m ² ), and adsorption is confirmed by further raising 2 mm from the reference position. It is also possible to determine that the sheet is an extremely thick sheet (a sheet of about 180 to 200 g / m ² such as a postcard in a range usable in a copying machine).

Here, the suction of the sheet is not detected by the suction detection sensor 50 in step S8, and S1 is detected.
2 is being executed, the upper limit detection sensor 44
Is performed, it is determined that the sheet P cannot be further lifted, and the sheet P is an extremely thick sheet or more, for example, it cannot be handled, and the sheet thickness detection is completed and the sheet P is set in the sheet feeding device 15. It is also possible to inform the user that the sheet that is being printed is impossible. .

When the above operation is completed, the detection of the sheet thickness is completed, and although not shown in the figure, the elevating mechanism is operated to set the uppermost sheet P to the reference position in order to set the sheet feedable state. To hold. If the position detection sensor 43 is not ON, the ascending operation is executed, the position detection sensor 43 is stopped in the ON state, and the standby state is maintained in this state. That is, the uppermost sheet P is held at the reference position.

Further, if the position detection sensor 43 is in the ON state, it may exceed the reference position. Therefore, once it is confirmed that the position detection sensor 43 is in the OFF state, the raising operation is executed and the ON operation is performed. By stopping in this state, the uppermost sheet P can be positioned at the reference position.

As described above, the thickness of the sheet P is detected in advance before feeding, and the sheet is held at the reference position to wait for feeding. Then, if there is a sheet feeding command, the sheet feeding device 15 performs sheet feeding control according to the detected thickness. For example, when the detected sheet is thick, it takes time to adsorb the sheet P to the sheet feeding belt 152, so it is preferable to perform control to increase the suction force. for that purpose,
By adjusting the opening / closing angle of the opening / closing valve 158, the flow rate of air can be controlled to increase. Alternatively, the suction fan 15
By increasing the rotation speed of 6, the air flow rate for suction can be increased.

Further, not only the suction force to the paper feed belt 152 can be adjusted, but also the discharge force for levitating the sheet can be adjusted. Therefore, the opening / closing angle of the opening / closing valve 166 is adjusted to increase the flow rate of the air blown from the nozzle 62 side, or the rotation speed of the discharge fan 164 is increased. As a result, even a thick sheet can be steadily levitated in the same manner as a thin sheet, and the suction operation on the sheet feeding belt 152 can be promoted. Further, by blowing air on the stacked sheet bundle, the separating effect can be enhanced, and the effect of adsorbing only the uppermost sheet P to the sheet feeding belt 152 can be enhanced. Then, if the flow rate of the air blown from the nozzle 63 is increased to prevent double feeding of the sheet adsorbed on the paper feeding belt 152, the paper feeding belt 15
The uppermost sheet P adsorbed by 2 is also separated. Therefore, by adjusting the opening / closing angle of the opening / closing valve 163 provided on the nozzle 63 side, the air at the leading end of the sheet can be blown at a predetermined air flow rate to separate a plurality of sheets.

The above-mentioned control can be performed by detecting the thickness of the sheet in advance, so that the sheet can be more reliably attracted to the sheet feeding belt 152, and at the same time, the time for attracting the sheet can be shortened. In addition, the separation effect of the sheets can be enhanced and the single sheet feeding can be performed more reliably.

According to the embodiment described above, the elevating mechanism, the various sensors for detecting the sheet, and the like are members that have been provided in the past, and by effectively utilizing these, the loading tray 151 can be used in advance.
The thickness of the sheets P stacked on the sheet can be detected.

Therefore, the sheet thickness is detected by lowering the loading tray 151 from the reference position in the sheet feeding state and gradually raising it. for that reason,
It is necessary to set the uppermost sheet to the reference position again after detecting the thickness. Therefore, this can be solved in the embodiments described below. That is, the thickness can be detected with the loading tray 151 set in advance at the reference position without controlling the lifting of the loading tray 151.

(Second Embodiment) Next, the structure of a sheet thickness detecting device capable of eliminating the disadvantages of the above-described embodiment of the present invention will be described.

In particular, FIGS. 4 and 5 show a suction detection sensor 50 for detecting the suction state of the sheet in order to detect the sheet thickness.
The sensor 50 is also disposed so as to face the leading end portion of the stacked sheets in the sheet feeding direction as described above.

The suction detection sensor 50 is usually provided to detect the sheet sucked by the paper feed belt 152, and outputs a signal for rotating the drive roller 152a of the paper feed belt 152 by confirming the suction state. by doing,
The sucked sheet P is being fed.

The suction detection sensor 50 is arranged between the paper feed belts 152, particularly on the paper feed side and on the nozzle 163 side for ejecting air. The adsorption detection sensor 50 is an optical sensor that has a light emitting element and a light receiving element provided side by side, and the light from the light emitting element is applied to the sheet that is the object to be measured, and the reflected light is received by the light receiving element. The presence of the sheet can be detected.

Further, the suction detection sensor 50 is the paper feed belt 1
The maximum amount of received light is obtained in the state of being adsorbed on 52, and the output from the light receiving element is maximized. Utilizing this, as shown in FIG. 5, air can be blown from the levitation discharge nozzle 162 to grasp the thickness of the sheet P according to the amount of light received when the uppermost sheet P is levitated. That is, the output value from the light receiving element is proportional to the levitated state.

On the other hand, the thicker the sheet P, the heavier the sheet P is, and therefore, the position where the sheet P is levitated becomes lower if the flow rate of air is constant. On the contrary, the sheet P is thin or the floating position is high. Therefore, as shown in FIG. 8, the thinner the sheet P, the larger the output of the suction detection sensor. For example, ordinary sheet thickness (about 70 to 80 g / m ² ) or 6
In the case of a thin sheet having a thickness of about 0 g / m ² , it can be determined that the sheet is thin or thick with the output reference Vc from the light receiving element as a boundary. In the case of an extremely thick sheet P such as a postcard, it is about 180 to 200 g / m ² , and even if it is struck by a constant air flow rate, the levitation amount is small and its output is very small. Therefore, as described above, the thickness of the sheet P corresponding to the output V of the detection sensor 50 can be easily grasped without simply determining whether it is thick or thin.

That is, if the sheet P is lighter than 60 g / m ² , the output is large and it can be determined that the sheet P is extremely thin. Further, when an output of about the reference Vc is obtained, it is determined as the normal thickness sheet P, and when output between the reference Vc and the output due to the thickness of the extremely thin sheet P is determined as the thin sheet P. However, if the output is obtained below the reference Vc up to the extremely thick sheet P, it is possible to easily discriminate the five-stage sheet P as the thick sheet P.

When detecting the levitation state of the uppermost sheet P stacked on the loading tray 151, the ejection amount of air for levitation is an air flow rate that is stable in the levitation state of the sheet P. Is best. In other words, if the floated sheet P is turbulent and wavy, the output of the adsorption detection sensor 50 is not stable and erroneously detected. Therefore, the flow rate of air from the levitation nozzle 162 discharged from the discharge means 160 is normally adjusted in a stable state. That is, the shape of the opening of the duct 165 and the discharge fan 1
By adjusting the number of revolutions of 64 and the like, the uppermost sheet P is levitated to a certain position by the air ejected from the levitation nozzle 162, and the ejection amount is adjusted in advance so as to maintain this state. There is.

On the other hand, if there is an air flow from the separation nozzle 163 or the suction portion, if the sheet P is levitated by blowing air from the levitating nozzle 162, the levitating state is not stable. Therefore, the separation nozzle 16 is also provided.
It is optimum to detect the levitation state in the state where the on-off valve 163 is closed to discharge the air of No. 3 and the operation of the suction means 154 of the sheet feeding belt 152 is stopped.

Moreover, when the uppermost sheet P is levitated by the levitating nozzle 162, the sheet P particularly at the tip end portion
The floating state of the sheet P is very stable, but the floating state of the sheet P at the rear end portion is not stable, and the sheet P may flutter or wave. For that reason, it is important to dispose the suction detection sensor 50 at a position facing the vicinity of the leading end of the sheet P of the sheet P.

Next, the thickness detection control of the sheet P shown in FIG. 9 will be described.

First, in order to replenish or replace the sheet P on the loading tray 151, the loading tray is pulled out to the outside. This pull-out direction is the direction opposite to the paper feed direction (S
20). In this state, sheets P having a desired size are stacked on the loading tray 151 and inserted into the main body of the copying apparatus 1. In this insertion state, the insertion can be detected (S21) by the ON operation of the conventional mounting detection switch. After this detection, the sheet P is raised to the optimum position (S22).
For that purpose, the elevating motor 46 of the elevating mechanism is driven to raise the loading tray 151. When the sheet P is raised to the reference position, which is the optimum sheet feeding position, the position detection sensor 43 operates and stops in this state.

In this control flow chart, the suction detection sensor 50 is also used, and the optimum reference position is obtained by detecting the amount of reflected light at the position of the uppermost sheet P which is the optimum position according to the output state of the suction / compression sensor 50. The seat P is raised. Therefore, the output of the suction detection sensor 50 is captured when the mounting tray 151 starts to move up (S23).
This output is compared (determined) with the output at the optimum reference position, and if it is not the optimum reference position, the ascending operation is continued. This operation is repeated, and when the value (Vh) corresponding to the optimum reference position is output from the suction detection sensor 50, this step is skipped, and the loading tray 151 is skipped.
Stop the ascending movement of. That is, the drive of the lifting motor 46 is stopped.

When the control of the optimum reference position described above is completed,
The sheet P is levitated in order to detect the thickness of the sheet P. For that purpose, the discharge fan 164 is driven, and in particular, the opening / closing valve 167 of the separation nozzle 163 is closed, and the floating nozzle 1
Air is discharged from 62. Air is blown to the uppermost sheet P stacked by this air ejection, and the sheet P is levitated (S26). After this operation, in order to detect the thickness of the floated sheet P, the output state (voltage value) of the adsorption detection sensor 50 is fetched (S27).

It is compared whether or not the fetched output voltage (V) is larger than the reference output Vc as shown in FIG.
In this comparison result, when the output voltage V of the suction detection sensor 50 based on the reflected light from the floating sheet P is smaller than the boundary reference voltage Vc, the floating position is low (far from the suction detection sensor) and is a thick sheet. It is determined that it is P (S30). Further, when the sheet P is thin, the floating position is high (close to the adsorption detection sensor), and its output becomes equal to or higher than the reference voltage Vc. Therefore, it is determined that the sheet P is thin (S29), and this operation is stopped. This stop means that the discharge fan 164 is stopped in order to stop the discharge of the air from the levitation nozzle 162, and the on-off valve 1
Close 66. The valve 166 may not be closed or may be open.

As described above, the thickness of the sheet P can be detected. In this thickness detection, in step S28, two types of sheet P thickness, thick or thin, are detected as in the first embodiment. However, as described above, the output of the adsorption detection sensor 50 is detected. It is also possible to perform five types of thickness detection depending on the voltage.

In this embodiment, the sheet P
Is detected and the thickness of the sheet P is detected according to the detected value, it is necessary to return the loading tray 151 to the optimum reference position of the uppermost sheet P as specified in the first embodiment. Without detecting the thickness of the sheet P,
There is an advantage that it can be set to the ready state of the paper feeding state as it is.

If the sheet feeding device 15 is selected according to the detection of the thickness of the sheet P, the control according to the detected thickness of the sheet P can be performed. For example, sheet P
If it is determined that the sheet P is thick, the floating position of the sheet P is low, and therefore control can be performed to increase the suction force when the sheet P is sucked. Further, in order to keep the levitation state at a fixed position, it is possible to control so that the amount of air discharged from the levitation nozzle 162 is increased.

Further, the position of the loading tray 151 can be controlled according to the thickness. In other words, when it is determined that the sheet P is thick, the floating position of the sheet is low, so that the suction time when sucking the sheet P to the sheet feeding belt 152 becomes long or the sheet cannot be sucked. It is also possible to raise to a position a little higher than the position and stand by. This is the lifting motor 46 as described above.
It is also possible to set the position raised by about 2 mm as the second reference position in the case of a thick sheet. In this case, even the thick sheet P can be sufficiently sucked, and thus the sheet can be fed without causing a feeding failure.

Here, in order to stabilize the state at the time of sheet feeding, the driving acceleration of the sheet feeding belt 152 is controlled so that the sheet P
It is possible to stably feed the sheet regardless of the thickness of the sheet.

Particularly when the sheet P is thin, the acting force to attract the sheet P to the sheet feeding belt 152 is strong, and even if the sheet feeding belt 152 starts driving, the sheet P is attracted without slipping on the belt 152. It will be fed in the state. However, when the sheet P is thick, the attraction force is weak, and slippage between the sheet P and the belt 152 is considered.

Therefore, as shown in FIG. 10, the acceleration of the sheet feeding belt 152 is changed according to the thickness of the sheet P. That is, when the sheet P is thick, the acceleration control is gradually performed so that the time required for the sheet P of the copying apparatus main body to rise to the conveyance speed is increased. Further, when the sheet P is thin, the acceleration is increased so that the time to reach the conveyance speed is shortened. According to this, when the sheet P is thick, the suction sheet P is fed in a state of following the sheet feeding belt 152 because the sheet P is gradually accelerated, and thereafter, even if the conveyance speed is reached, slipping occurs. No worries.

The acceleration for raising to the above-mentioned conveying speed is such that after being conveyed by the paper feed belt 152, it is accelerated to a speed that coincides with the conveying speed before being bitten by the conveying roller 34 arranged on the copying machine main body side. Let Therefore, in the case of the thin sheet P, the time required to rise to the transport speed is short, and in the case of the thick sheet P, it is long.

The above acceleration control can be similarly performed in the thickness detecting device according to the first embodiment, and thus the same effect can be obtained. Here, in order to control the acceleration, switching for raising the driving motor 53 to a constant speed shown in FIG. 3 is performed.

[0093]

As described above, according to the paper feeding device of the present invention, it is possible to make a determination according to the state of the loading tray for increasing the thickness of the sheet. The sheet thickness can be detected.

Further, the thickness of the sheet can be finely detected according to the degree to which the loading tray is raised.

Moreover, since the thickness can be detected by detecting the floating state of the sheet while the loading tray is set at the optimum reference position, more stable thickness detection can be performed and the loading tray can be re-mounted. You don't need a set.

Further, the floating state detection sensor has the advantage that it can also be used as a sensor for detecting the suction state of the sheet, and can also be used as a sensor for setting the sheet tray at the optimum reference position.

Therefore, in order to stabilize the sheet feeding operation in accordance with the detected sheet thickness, the air flow rate control or the sheet feeding control is performed to prevent the sheet feeding failure and the double feeding, and it is possible to feed one sheet. You can

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of the initiation of copying provided with a sheet feeding device of the present invention.

FIG. 2 is a cross-sectional view showing an example of a sheet feeding device according to the present invention.

FIG. 3 is a plan view showing a state seen from above the sheet feeding device in FIG.

FIG. 4 is a cross-sectional view showing an entire sheet feeding apparatus using air according to the present invention.

5 is a front view showing a state of a sheet feeding belt position in FIG.

FIG. 6 is a schematic view showing details of an elevating mechanism on a placing tray formed by stacking sheets according to the present invention.

FIG. 7 is a flowchart showing a control operation by sheet thickness detection according to the present invention.

FIG. 8 is an output characteristic diagram for explaining another embodiment for detecting the thickness of the sheet in the present invention.

9 is a flowchart showing a control operation for detecting the thickness of a sheet according to another embodiment of the present invention using the characteristics shown in FIG.

FIG. 10 is a diagram illustrating an example of sheet feeding control according to sheet thickness detection.

[Explanation of symbols]

 15 Paper feeding device 151 Loading tray 152 Feeding belt 154 Suction means 155 Suction part 156 Suction fan 160 Discharging means 161 Discharging part 162 Floating (discharging) nozzle 163 Separation (discharging) nozzle 160 Discharging fan 40 Wire (mounting tray lifting) 43) Position detection sensor for reference position detection 46 Elevating motor 47 Slit disk 48 Optical sensor 50 Adsorption detection sensor (optical sensor)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Koichi Yamauchi 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture Sharp Corporation (72) Inventor Kazuyuki Ogita 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture Incorporated (72) Inventor Takeshi Iwamoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) In-house Masato Kanazawa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Osaka

Claims (5)

[Claims] 1. A sheet feeding unit for feeding the uppermost sheet on a loading tray, a suction unit for sucking the uppermost sheet to the sheet feeding unit by air suction, and a leading edge of the sheet to be fed. A sheet feeding apparatus comprising: an air ejecting unit that blows air to float and separate the air; and a driving unit that drives the sheet feeding unit to feed a sheet adsorbed to the sheet feeding unit. Is provided so as to be movable up and down, and elevating and lowering control means for elevating and lowering the loading tray, and a position for detecting a state in which the uppermost sheet on the loading tray reaches the sheet feeding reference position when the loading tray is raised. A detection sensor; a control means for lowering the placing tray by a predetermined distance in response to the reference position detection by the position detection sensor; and a control means for operating the suction means at the lowered position to perform suction of the uppermost part; Up A suction detection sensor that detects the state of being sucked by the paper feed belt, and a sheet that determines the thickness of the sheet according to the position of the uppermost sheet on the loading tray in response to the suction detection of the suction detection sensor. A sheet feeding device using air, which is provided with a sheet thickness detecting device having a thickness determining means. 2. A sheet feeding means for feeding the uppermost sheet on the loading tray, a suction means for adsorbing the uppermost sheet to the sheet feeding means by air suction, and a leading edge of the sheet to be fed. A sheet feeding apparatus comprising: an air ejecting unit that blows air to float and separate the air; and a driving unit that drives the sheet feeding unit to feed a sheet adsorbed to the sheet feeding unit. Is provided so as to be movable up and down, and elevating and lowering control means for elevating and lowering the loading tray, and a position for detecting a state in which the uppermost sheet on the loading tray reaches the sheet feeding reference position when the loading tray is raised. A detection sensor; a control means for operating the air ejection means for levitation in response to the reference position detection of the position detection sensor; a levitation position detection sensor for detecting the levitation position of the seat; Sheet feeding using air having a sheet thickness determination means for determining the thickness of the sheet in accordance with the output from the sensor, the sheet thickness detecting device provided with a device. 3. A sheet feeding apparatus using air according to claim 1, wherein the suction amount or the discharge amount of air is controlled according to the detected sheet thickness. 4. The sheet feeding apparatus using air according to claim 1, wherein the acceleration of the sheet feeding belt is controlled according to the detected sheet thickness. 5. The sheet feeding apparatus using air according to claim 2, wherein the sheet floating position detection sensor is an optical sensor and also serves as a reference position detection sensor for the uppermost sheet.